Look at This ……….

Written by Sierra Bullets Ballistic Technician Duane Siercks

A few months back, I was spending a Saturday morning at the local gun shop where I hangout when there really isn’t anything better to do. Upon arriving I walk in behind the counter to view the selection of goodies setting in the rack. Yeah, they still let you do that in some places. Anyway, as I handled each interesting piece, I noticed a heavy barreled Remington 700 Varmint setting there and it looked very clean upon first notice. I take it from the rack and glance over the stock. The stock was way above average for cleanness and grain and color. I then looked to see what caliber this jewel was chambered in. I am hoping it is something very interesting. I know all the normal calibers that were produced in this configuration, so to my amazement I find that this gun is not one of the normal chambering at all. It is actually a custom barreled gun chambered in 7mm TC/U. This cartridge can be found in many T/C Contender hand guns, and was a very common chambering used in Metallic Silhouette competitions. This cartridge is made by expanding the neck of a 223 Remington case to 7mm/.284 diameter. You then fire-form the case in the chamber of the 7 TC/U firearm.

7mm_Sierra_Cartridge
Sierra_7mm_TCUThe 7mm TCU, like the rest of the TCU family, is based on a necked up and fireformed .223 Remington case. By far the most popular of Wes Ugalde’s wildcats, the 7mm TCU has dominated the “production” category of both NRA and IHMSA silhouette competition. This should come as no surprise, since the 7mm TCU has virtually everything going for it. It is superbly accurate, and not at all finicky to load for. Its parent cases are readily (and cheaply) available, and case forming is a snap. It delivers reliable knockdown on the 200 meter rams without undue recoil. In short, it is exactly what is required for the silhouette game. The 7mm TCU is the most widely used (and still the most winning) cartridge in the “production” class today. Cases for the TCUs are formed by opening up the case necks on .223 Remington cases with a tapered expander. This is best accomplished with new, unfired brass. Frequently, .223 cases that have been reloaded a few times before forming will split at the neck during the expanding process. This can be minimized by using new cases, or by annealing older cases before attempting to expand the case mouths. The initial firing will blow the shoulders and body out to its final TCU dimensions. Once cases are formed, we strongly recommend neck sizing only, unless chambering becomes difficult. Contenders perform best when headspace is held to an absolute minimum, so great care must be taken to avoid setting the shoulder back during resizing. This simple step will extend case life, increase accuracy, and ensure reliable ignition. Silhouette shooters will find that the 140 grain Spitzer or Spitzer Boat Tail are outstanding performers for everything out to the rams. The heavier 160 grain Hollow Point or Spitzer Boat Tail will provide greater momentum for reliable knockdown on the heavier, tougher rams. Sierra produces a .284″ diameter 130 grain Single Shot Pistol bullet specifically for cartridges like the 7mm TCU. Even with these lightweight, thinly jacketed bullets, the TCU is at its best on deer sized game when used in barrels not shorter than 14 inches. Although the 10 inch barrels can be just as accurate as the longer barrels, they sacrifice enough velocity to make reliable expansion somewhat questionable. Within these limitations, the 7 mm TCU can be a reliable performer on deer, as long as shots are placed precisely. Copyright © 2003 Sierra Bullets, LLC.

7mm_RifleWhat a deal!! So now the quandary is to figure out how I can acquire this gun. You can’t just whip out the checkbook and pay up. It requires finesse in calculating and scheming. Anyway….. I don’t want to make this last forever.

I take my find home and begin to plan what I want to do with this unusual firearm. I begin to work up some loads and found with the Sierra 7mm 100 grain HP that this gun will certainly shoot very well. With the 2nd load that I tried it was grouping a very nice .433” group for 5 shots at 100 yards. I can see already that this gun is going to be one of my favorites. The velocity was 2622 fps. For short range varmint calling, this should work out superbly. Now……… I wonder what is setting at the gun shop today……

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4 Responses to Look at This ……….

  1. pAUL a. gANTT ii says:

    Just thought I would let you know that I am considering building an AR chambered for the 7TCU.

    Like

    • Pj says:

      Hey man I am sitting at the house can’t sleep and I thought I had the greatest idea, to make an ar chambered with a 233 case necked up to 7mm. Anyways after figuring this out how did your project turn out?

      Like

  2. Don Crawford says:

    Karen Crawford of Bradford, PA holds the Highpower Silhouette Ram Record for Women. A 722 actioned, Douglas Barrelled 7MM-TCU throated out to seat 168 MK and allow 26.8 of H335. OAL of 2.70. 2.5 inch groups at 500 meters. 2256 fps.

    Like

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